Process of annealing



Sept. 15, 1931.

H. ROBERTSON PROCESS OF ANNEALING 22. 1927 3 Sheets-Sheet 2 OriginalFiled Oct.

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Sept. 15, 1931. H. M. ROBERTSON PROCESS OF ANNEALING 3 t w n 0 S a 6 h Sn. 3 1 7 2 9 l a 2 C 0 d a e an 1, 1 F l a n i E .n o J I v 21 I MN hmW;

Patented Sept. 15, 1931 PATENT OFFICE HARRY M. ROBERTSON, OF CLEVELAND,OHIO PROCESS OF ANNEALING Original application filed October 22, 1927,Serial No. 228,082. Divided and this application filed January 31, 1930.

This invention relates to a process of heat treating or annealing bodiesor castings, such as malleable iron castings and the like.

One object of the invention is to provide an improved process ofannealing, whereby castings may be annealed in a relatively short periodof time.

Another object of the invention is to provide an improved process ofannealing in a nonoxidizing atmosphere.

Other objects of the invention will be apparent to those skilled in theart to which my invention relates from the following description takenin connection with the accom- 5 panying drawings, which show oneapparatus capable of carrying out the steps of my process.

Fig. 1 is a top plan view of the apparatus, such View showing twoapparatuses arranged side by side. 7

Fig. 2 is a side elevation.

Fig. 3 is a front elevation.

Fig. 4 is a section (enlarged) on the line 4-4 of Fig. 2.

Fig. 5 is a section on the line 5-5 of Fig. 4.

Fig. 6 is a section onthe line 6-6 of Fig. 4.

ln the drawings, 1 indicates a suitable bed of concrete havinginsulating coverings 2, 3, of suitable fire-resisting materials, thelatter forming the flooring for the oven or chamber 4. In theaccompanying drawings I have shown two chambers 4 arranged side by sideupon a single bed 1, such arrangement being preferable since a singleexhaust means or chimney (to be later referred to) may be utilized forboth chambers and thus reduce the cost of installation.

Each chamber 4 is formed by an end wall 5 and side walls 6, 6a, eachformed of suitable fire-resisting material or materials, such as firebrick 6 and an outer wall of brick 7 formed of suitable material such asdiatomaceous earth. The inner side walls 6a of the two chambers areseparated by a suitable insulation 8 which permits of expansion of thesewalls. Extending from the end wall 5, at an elevation above the bed 1,is a base 9 supported at its outer end by suitable uprights 10. The base9 may comprise longitudinal and transverse channels or the like,

Serial No. 424,871.

other suitable material. The bed 11 co-operates with extended portions60: of the side walls 6, 6a, to form a fire chamber 12. Each of theannealing chambers 4 and its fire chamber 12 are covered by a top orroof of fire brick 13 which'is covered with a suitable insulation, suchas diatomaceous earth powder. The side walls 6m and top of the firechamber preferably converge, and at their outer portions these walls andthe bed 11 form. an opening 14 for a burner or other suitable means forsupplying and efl'ecting combustion of fuel, for example, powdered coalsupplied under pressure in any well known manner. That end of thechamber 4 opposite to the fire chamber 12 is open, as shown at 15, topermit the pots containing the castings to be annealed to be moved intothe chamber 4-and removed therefrom by suitable apparatus, such astrucks. The opening 15 is closed by a door or wall 16 and the lattersealed when the apparatus is set in operation.

17 indicates a main flue formed in the upper portion of each side wall6, 6a, and extending longitudinally thereof, and substantially from endto end of said wall, the side wall being thickened and extended upwardlyabove the top 13 to provide for the flue 17. 18 indicates flues formedin each of the side Walls 6,- 6a, connected at their upper ends with theadjacent main flue and leading downwardly (preferably vertically) to orbelow the flooring 3 and each connected with one or more exhaust ports19, 19a, formed in and leading through the side walls adjacent theflooring 3. I preferably provide a pair of inlets or ports 19, 19a foreach flue 18. The vertical flues 18 adjacent to the opening 15 areconnected at their lower ends by a transverse flue 20 formed in theflooring 3 and bed 1, the top wall of this flue comprising a grating 1aof suitable construction disposed in the plane of the flooring 3,whereby any air which may leak into the chamber along the lower portionofthe opening 15 may flow through the grating into the collecting flue20 and be exhausted through the flues 18, 17 the grating permitting theair to flow through it and also providing a suitable wall or flooringfor the trucks or other apparatus to run over. By the provision of thisflue at that end of the chamber 4 remote from the heating means itinsures a suflicient supply of the hot gases to this portion of thechamber 4. The pairs of exhaust ports 19, 19a, connected with the flues18 are spaced from each other preferably uniformly from end to end ofthe chamber 4.

As shown in Fig. 5, the upper ends of the vertical flues 18 are slightlysmaller in width than the width of the flues 17. This permits the bottomof each flue 17 at opposite sides of the adjacent fine 18 to form a seatfor a valve or damper 18, preferably comprising a relatively heavy platewhich may be raised and lowered to close or open to any desired extentthe adjacent flue 18, and thus control the exhaust of the products ofcombustion therethrough. The dampers 18 are operated in a manner to belater set forth. One end of each flue 17 (preferably that end adjacentthe fire chamber 12) is extended upwardly, as shown at 21 and the latteris connected to a manifold 22 disposed transversely of and mounted onthe top 13. The manifold may be suitably insulated on its inner surfaceto protect its metal shell. As shown, I provide one manifold 22 for theflues 1717, l7l7, formed in the side walls 6, 6a, for both chambers. Themanifold 22 is connected by conduits 23, 23a, with a main conduit 24,which in turn is connected with the inlet of a suitable suction orexhaust mechanism 25, preferably comprising a casing and a fan mountedtherein. The fan is connected to the shaft of a motor 26 and driventhereby to provide a forced draft to exhaust the products of combustionand gases from the chambers 4. The suction mechanism 25 and motor 26 aremounted on a suitable support 27 carried by an upright 28.

The outlet from the casing of the suction mechanism 25 is connected by aconduit 29 with a chimney or stack 30 through which the products ofcombustion drawn from the chamber or chambers 4 are forced anddischarged into the atmosphere.

The top 13 is formed with one or more inlet openings 31, and theseinlets have connected to them, supply flues 32, connected through acommon supply flue 33 to the stack or chimney 30.

34 indicates a valve or slide damper arranged to control the flow of theproducts of combustion and heat through the conduit 24 under theinfluence of the suction fan.

35 indicates a valve or damper mounted in the stack 30 above theconnection of the supply flue 33 therewith and 36 indicates a valve ordamper mounted in the fine 33. The dampers 35 and 36 are preferablyindependently operated. In one method of operation the damper 36 isclosed and the damper 3:) opened, so that the products of combustiontsaaeae and gases may be discharged into and through the stack 30; butwhen desired, for reasons to be later set forth, the damper 35 is closedand the damper 36 opened, in which event the products of combustion arereturned under pressure to the chamber l to effect a nonoxidizingcondition therein.

The dampers 18 may be operated by any desired means; but preferably eachdamper 18' has connected to it one end of a flexible member, such as achain 37. The chain 3 leads upwardly through an opening in the top wallof the adjacent conduit 17 and leads over a sheave 38, then around asecond sheave 39; from the-latter sheave the chain leads downwardly andaround a third sheave 40 and then horizontally to an operating stationat some convenient point, for example, one end of the a paratus(preferably that end adjacent the lire chamber); all of the chains forcontrolling the dampers for each chamber 4 leading to oneoperatingstation. At the operating station means are provided forsecuring each chain and iii-one of several predetermined positions, sothat the damper connected to it may be closed, or held in full openposition or a partially open position. By preference the dampers areheavy and therefore self closing under the influence of gravity, so thatpull on any chain will lift the damper connected to its inner end to thedesired position. The free end of the chain is connected to a bar or rod41 preferably terminating in a handle and slides endwise through anopening 42 formed in a plate 43 suitably connected to the walls of theapparatus. The rod 41 is provided with a series of teeth or lugs one ofwhich engages the face of the plate 42 to hold the rod a]. at anyposition to which it is pulled or slid, to raise the adjacent damper. Byswinging the rod 41 in its guide opening 42, it may be released from theplate and allowed to slide inwardly due to the weight of the' adjacentdamper when it is desired to close the latter. Each damper 18 may beraised and lowered any desired distance and by their control oradjustment the influence of the exhaust mechanism 25 is effective toinsure adequate circulation of the products of combustion throughout theannealing during each annealing operation. I

In carrying out my process, either or both chambers are first chargedwith pots tilled with the castings to be annealed, the chamber closedand sealed, the damper 36 closed and the dampers 3d and 35 moved to fullopen position, and dampers 18' opened to the desired extent. Next theheating means are then ignited'and the motor 26 started to drive theexhaust fan. Since the inlet of the casing surrounding the fan isconnected through the conduits 24, 23, 23a and manifold 22 with thefines 2l1718 and the latter ha e inlet openings or ports 1919a,

bodies.

leading from the annealing chamber 4, the products of combustion will bedrawn or sucked through these ports and discharged from the fan casingthrough the stack to the outside atmosphere. In this etc of my processthe temperature of the chamber 4 is raised to approximately 1600 or 1650degrees F. (depending on the nature of the bodies being treated). Next,the supply of fuel is Feduced suificiently and the damper 3,4 partiallyclosed to reduce the suction effect and rate of exhaust of the productsof combustion to produce and maintain a soaking temperature within andthroughout all portions of the chamber during the period required toeffect annealing. Next, the supply of fuel to the heating means isreduced or cut-ofi' so as to effect a relatively slow cooling; finallythe damper 34 is fully open and supply of fuel cut off (if not alreadycut off) to permit of rapid cooling of'the chamber' and In accordancewith my improved process, and the preferred form of construction forcarrying out the process, the exhaust ports are disposed at the lowestand most remote portions of the annealing chamber 4, that is, adjacentits flooring and at substantially uniformly spaced points along itsopposite sides and across the fioor adjacent the receiving opening 15 atthe farthest and lowest point from the heating means. In this form ofconstruction, the products of combustion are caused to circulate to allportions as well as the lowestportion of the chamber and substantiallyuniformly over its entire area, with the result that heat is applied toand over and around all of the filled pots. In the use of my improvedapparatus and the carrying out of the process therewith, I have beenable to reduce the total period of time required for heating the chamberup to the desired degree of temperature (to-wit, substantially 1600 or1650 degrees, F.) and the time required for treating or annealing thecastings is reduced also materially as compared to apparatus of thischaracter of which I have knowledge. By reducing the total period theapparatus is in use for'each charglng, a great saving of fuel resultsand the apparatus can be recharged and operated a great number of timesin any predetermined period which has the effect of increasing thecapacity for any given installation. It will be noted that in the use ofmy improved apparatus, since the circulation of the products ofcombustion is ef- .fected by a power operated suction or exhaustmechanism, the chamber 4 may be enlarged to increase the capacitywithout increasing the size of the fire chamber, which tends to reducethe cost of operation.

When it is desired to produce a non-oxidizi ing atmosphere in thechamber, I prevent air or oxygen or any substantial amount thereof fromcoming into contact with the pots .products of combustion into the upperporduring the period the chamber is being heated and during the periodof annealing. To carry out these steps in this manner, I return theproducts of combustion, under pressure to the chamber 4, preferably at alevel above theoutlet ports. This form of my method iseffected byadjusting the dampers 35, 36, as already set forth, so that the productswill be forced through the supply fiues 33, and 32 and inlets 31 to thechamber4. In this latter method, deterioration of the pots is reduced orsubstantially eliminated and hence permits them to be mantained in usefor an indefinite period. This application is a division of myapplication Ser. No. 228,- 082, Letters Patent N 0. 1,7 52,697, datedApril 1, 1930.

To those skilled in the art to which my invention relates many changesin construction and widely differing embodimentsand applications of theinvention will suggest themselves without departing from its spirit andI scope. My disclosures and the description herein are purelyillustrative and are not intended to be in any sense limiting.

What I claim is:

1. The herein disclosed process of annealing which consists in charginga chamber with filled pots, then in supplying heat and tion of saidchamber and simultaneously exhausting the products of combustion fromthe lower portion of said chamber at a plurality of points disposedadjacent the bottom portion of said chamber and returning said productsof combustion to and discharging them directly into the upper portion ofsaid chamber. a

2. The herein disclosed process of annealing which consists in supplyingheat to a charged chamber and simultaneously exhausting the products ofcombustion from the lower portions of the chamber at a plurality of.points by forced draft to raise the temperature of the chamber to thedesired degree and conducting the products to and discharging them intothe upper portion of the chamber to produce a non-oxidizing atmospheretherein, then in reducing the heat supply to the chamber and rate ofexhaust therefrom to produce suitable soaking conditions in the chamber,and then slowly cooling the chamber.

In testimony whereof, I have hereunto subscribed my name.

